1. Technical Field of the Invention
The present invention generally relates to an electrospark machining system, a device for mounting an electrospark machining electrode, and a method of using an electrospark machining system, and more specifically to a system which eliminates the need for using a surface of an electrode blank as a reference surface when an electrode blank is formed into a shaped electrode and during the electrospark machining of a workpiece using the thus-shaped electrode.
2. Description of Relevant Information
Electrospark machines and electrodischarge machines (also known as EDM machines) are presently widely used, e.g., to manufacture high precision molding dies for injection molding machines; these electrospark machines are used because of their high machining efficiency. In these systems, the shape of a shaped electrode is accurately reproduced on a workpiece to be machined. Generally, a blank from which the electrode is formed is machined by a wire cut electric spark machine, a cutting machine, or other machine tool, in order to provide a shaped electrode having a desired shape.
A molding die having a simple profile can be machined, e.g., by a single shaped electrode. However, a molding die having a complex profile cannot be machined by only a single, shaped electrode. Specifically, such a complex molding die can instead only be machined by a composite machining system, using a plurality of shaped electrodes.
Generally speaking, the number of shaped electrodes used in a composite machining process can be reduced or decreased if shaped electrodes having three-dimensional complex profiles could be produced and used. However, in practice, an increased plurality of shaped electrodes are needed to produce shaped electrodes having complex three-dimensional profiles, thereby resulting in an apparatus which would be difficult to maintain.
During the conventional machining process of a shaped electrode, six faces of a rectangular parallelepipedic electrode blank are ground in order to provide six reference surfaces which are perpendicular to each other. The electrode blanks can be attached to an electrode forming machine, e.g., a wire cut electric spark (hereinafter electrospark) machine, with the assistance of the reference surfaces on the blank. When the electrode blank is subjected to a two- or three-dimensional machining process, the reference surfaces must be changed in order to again attach the blank to the electrode forming machine.
In such a conventional machining process, as noted above, it is necessary to adjust the mounting position of the electrode blank, including but not being limited to centering the blank, and/or creating parallelism or perpendicularity between the reference surface or surfaces and the surface being machined at each change of direction during the machining process. The operations needed to make such adjustments are difficult and troublesome. Accordingly, it is practically impossible to obtain a shaped electrode having a three-dimensional complex profile using conventional methods. Accordingly, during an actual machining process, the molding dies are machined by a composite machining device in which a large number of shaped electrodes having simple profiles are used.
The above-noted problems also occur during a machining process using an electrospark machine having a shaped electrode attached thereto. Specifically, when the shaped electrode is transferred from the electrode forming machine to the electrospark machine, unless the positional relationship of the electrode with respect to the electrode forming machine is exactly reproduced between the electrode and the electrospark machine, precise and exact machining by the electrospark machine cannot be achieved. In conventional processes, it is extremely difficult to exactly reproduce the identical positional relationship that the electrode had with respect to the electro forming machine when the electrode is positioned in the electrode spark machine; accordingly, the troublesome and difficult adjusting operations as noted above, e.g., the centering operation, must be effected after the electrode is transferred to the electrospark machine. Further, even after such an adjustment is made, an accurate reproduction of the positional relationship between the electrode and the electrode forming machine, on the electrospark machine, cannot be ensured.
One type of shaped electrode is used in which the direction of displacement of the electrode during the course of electrospark machining of a workpiece is perpendicular to the direction of machining of the electrode blank. Using this type of shaped electrode, in conventional processes, the shaped electrode is first machined by the electrode forming machine and removed from the electrode forming machine. Thereafter, the shaped electrode is attached to the electrospark machine after the direction of the electrode is changed by 90.degree.. It is, however, difficult to accurately set the electrode again in the electrospark machine. The failure to accurately position the electrode in the electrospark machine results in a failure to accurately reproduce the shape of the shaped electrode on a workpiece being shaped.